The present invention relates to a machine tool, especially a multi-station grinding machine for manufacturing drill bits and similar, elongate workpieces, the machine tool having a separation wall between a housing and a work space.
DE 198 44 793 A1 discloses a machine tool having multiple axesxe2x80x94in particular, five axesxe2x80x94for the machining of workpieces including, preferably, cutting work on workpieces with a work tool spindle which is arranged on a platform with, in particular, its length axis vertical to the surface of the platform, whereby the platform is linked via, preferably, six linkages with the work tool spindle as well as with the length variable machine legs which are themselves connected to the machine supports. A movable separation element is available which, on one side, is connected on its outermost periphery with a housing (not illustrated) and, on its other side, is secured to the periphery of the platform or is linked therewith. Via the separation element and the platform, the movement space for the machine legs and the joints or links is completely separated or segregated from the work space. Only the work tool spindle and, if present, the support or, respectively, the slot for the arrangement of the work tool spindle, extends through the separation element, or respectively, the platform, into the working space. Numerous connections for the actuation of the work tool spindle are arranged behind the platform in a dirt and debris-free movement space. In connection with this machine tool, the working space encloses the workpiece to be worked as well as the working tool pieces and a work tool exchanger, and those of their guides and drives which are exposed to possible contact with material remnants generated during the machining process and, in connection with high performance machine tools having high pressure in the working region, possible contact with injected coolant lubricating medium.
DE 199 26 668 A1 discloses, additionally, a multiple station machine tool for the manufacture of drill bits and other workpieces having spiral grooves, the machine tool having a base plate, a plurality of stations arranged on the base plate for the machining of workpieces as well as for the receipt of workpieces, a holder secured to the base plate having a support plate, drives fixedly secured to the support plate for vertically movable, axially extendable and retractable, and rotatable workpiece holders, a rotating table arranged above the support plate which is rotatable in a stepwise manner, a plurality of vertically movable, axially extendable and retractable vertical shafts supported on the rotating table for supporting thereon the workpiece holders, releasable couplings between the drives and the driven elements for controlling the rotative movement, as well as the height adjustment, of the shafts, releasable interlocking elements between the couplings and the rotating table, and actuation elements for the couplings and the interlocking elements for component exchange related, coupled disengagement of the interlocking elements, for coupling of the couplings for the drives of the workpiece holders during the machining of workpieces as well as for component exchange related grouped de-coupling of the couplings, and for interlocking of the interlocking elements during further actuation of the rotating table.
With this arrangement, the stations of the multiple station machine tool can perform differing machining processes such as, for example, the grinding of spiral grooves, the grinding of points including the finishing of pointed ends, the creation of eccentrically relieved or back cut surfaces on the drill bit edges and the drill bit outer surfaces and, finally, the placement and removal of workpieces.
Due to this arrangement with the drives on the support plate, the drives do not need to be moved in correspondence with the movement of the support plate during station exchange movements so that the connection of the drives with a CNC control and the supply of energy to the drives is simplified.
In connection with a station change effected via the turning of the rotating table, in order to avoid variations in the workpiece holdersxe2x80x94that is, in order to avoid turning or height variation in the workpiece holder during such change movementsxe2x80x94releasable couplings and releasing interlocking elements are provided. Through the interlocking elements, the workpiece holders are fixed in their positions, if the couplings are in a de-coupled disposition. Conversely, if the couplings are coupled together in connection with the release of the interlocking elements, there occurs no position movement of the workpiece holders.
This multiple station machine tool solves the problem of improving the production of such workpieces by permitting their production in a cost favorable manner which requires only relatively little dimensioning and which operates reliably. Moreover, easy access to all stations is possible with such a machine so that the inactive or dead time for the exchange of work tools or the changing out of other required support elements for the workpiece machining can be limited to the shortest possible time. Furthermore, the position of the workpieces remains unchanged during the station change movement. This known machine has proven itself in connection with the mass production of spiral drill bits and similar workpieces but, however, has revealed that the drives for the workpiece holders, as well as the shafts and couplings associated therewith, are not sufficiently protected against the material remnants which are carried off in connection with the machining of the workpieces or the cooling lubricating medium which is used in such machining processes.
In general, the protection of sensitive components of machine tools from the material carried off in connection with the machining and from the typically deployed lubricating material is particularly lacking, if the cooling lubricating material is ejected in high performance machine tools under high pressure into the working region, whereby the invention provides a solution to this problem by offering a machine tool, especially, a multiple station grinding machine for the production of drill bits and similar elongate workpieces, which is improved such that a practically total protection of the sensitive components is provided.
From the perspective of this problem, a machine tool is provided, especially, a multiple station grinding machine for the production of drill bits and similar elongate workpieces, which has at least one axially displaceable and rotatable workpiece holder which has its axial displacement and rotation drive in a sealed-off housing, at least one working tool arranged in a sealed-off working space, a sealing separation wall between the housing and the working space, at least one guide conduit arranged in sealing relationship in the separation wall for receipt of the workpiece holder, and guide elements for the workpiece disposed at the end of the guide conduit which extends into the working space.
The present invention provides a practical embodiment of the concept of a machine tool which is divided into at least two spaces of which one is the working space such as, for example, the grinding chamber, while the other additional space is sealed off therefrom and has therein the most important mechanical elements for the machine tool including a workpiece exchange device.
The guide conduit is, advantageously, guided in a sealed manner through the separation wall by a precision guide during its axial displacements.
In order to move a workpiece from the housing, in which the workpiece has been disposed on a workpiece holder, into the working space, the workpiece holder with the workpiece disposed thereon is guided along the guide conduit into the working space. In this manner, the guide element encloses the workpiece in such a complete sealing manner that practically no cooling lubricating material or material carried off from the workpiece can find access into the housing in which the mechanical elements are housed. A seal element is disposed between the guide conduit and the separation wall which permits axial movement of the guide conduit with the workpiece holder thereon, in the event that this is needed for the machining of the workpiece.
The machine tool can be configured such that it includes at least one horizontally moveable workpiece holder; however, the workpiece holder can also be configured to move vertically.
The present invention permits equally a machine tool with only one working station as well as a machine tool with several working stations to be used and can be used in connection with milling machines as well as in connection with grinding machines.
The guide conduit can, for example, be held in its extended-out position via spring biasing, in which event the guide conduit is carried along by the axial movement of the workpiece holder.
Preferably, however, an axial displacement drive can engage the guide conduit, the axial displacement drive being controlled such that it axially displaces the guide conduit synchronously with the displacement of the workpiece holder by another axial displacement drive during the workpiece machining.
In a preferred embodiment of the machine tool, the axial displacement drive for the guide conduit can be disposed in a sealed-off manner in the working space, if a carry conduit extends through the separation wall and has, on its end which extends into the working space, a support for at least one working tool and is configured for the axial displacement drive of at least one guide conduit.
This carry conduit can include, on an end thereof which extends into the sealed-off housing, a support for a rotatable multiple station workpiece exchange device, whereby this end is fixedly connected with the support plate for at least one workpiece holder and its drive.
In a preferred embodiment of the machine tool, the machine tool includes five working stations and corresponding work tools in the working space, five workpiece holders and their drives in the housing, five guide conduits extending through the separation wall, and a six armed workpiece exchange device in the intermediate space between the separation wall and the support plate, whereby five arms are each respectively arranged in the region of the five workpiece holders for effecting thereat the transfer over or receipt of a workpiece, and one arm is moveable into the region of a workpiece transfer over device.
In this manner, the five workpieces can be simultaneously machined with different work tools while a further workpiece is transferred over to a workpiece holder by the workpiece exchange device or is received from the workpiece holder by the workpiece exchange device.
The guide element in at least one guide conduit can be configured to be exchangeable in order to permit the customization of the guide element for different workpieces. The guide element can, for example, comprise a guide bushing, if only the end region of a workpiece is to be machined. If an elongate workpiece is be machined over substantially its entire length, the guide element can advantageously be supported over substantially the entire length of the workpiece on a portion of the guide conduit extending thereunder and comprising a half-open guide rail. In this manner, the workpiece can be worked on one side thereof while the opposite side thereof is supported by the guide rail.
The workpiece holder seals the bushing in its extended-out position, even if no workpiece is currently disposed in the workpiece holder.